Electromagnetic coils and terminal strips for such coils



Dec. 29, 1964 A ZA K 3,163,840

ELECTROMAGNETIC COILS AND TERMINAL STRIPS FOR SUCH COILS Original Filed Aug. 23, 1960 FIGZ A L BERT ZAC K I VENTOR.

ATTORNEY United States Patent 3,163,840 ELECTROMAGNETIC CUILS AND TERMINAL STRIPS FUR SUCH CQIJLS Albert Zach, Danvers, Mass, assiguor to Sylvania Eicctric Products Inc, a corporation of Delaware Continuation oif application Ser. No. 75,836, Dec. 14, 196i which is a continuation of application Ser. No. 51,333, Aug. 23, 1960. This application July 12, 1963,

Ser. No. 294,639

4 Ciaims. (Cl. 336--192) This application is a continuation of my copending application Serial No. 75,836, now abandoned, filed December 14, 1960, entitled Terminal Connector, which in turn is a continuation of my copending application Serial No. 51,333, now abandoned, filed August 23, 1960 entitled Electromagnetic Coil Contact.

This invention relates to electrical contacts which may be used in conjunction with electromagnetic coils and more specifically to a contact designed as a terminal strip for disposition at the ends of such coils.

Electromagnetic coils are well known to the art and have been fabricated in many forms. Generally these coils have been made by wrapping many turns of insulated wire around a core, and have frequently been too bulky for convenient use. A more recent innovation in the electromagnetic coil art which reduces this bulk is the so-called wafer coil. A method of manufacture of such coils is described in my copending application Serial No. 401,333, now Patent No. 3,113,374, filed December 30, 1953, entitled Electromagnetic Coils. As described therein, flat sheets of foil and of insulating material are mutually wrapped upon a removable core which is positioned on a lathe-like machine to form a large, elongated roll from which smaller, so-called wafer coils can be sliced. Lead-in wires are then afiixed to the wafer coils by soldering to the ends of the toil. Since after slicing, the wafer coils are frequently as thin as an eighth of an inch, and the thicknessof the foil is of the order of a ten-thousandth of an inch, substantial problems are presented in attaching the terminal wires to the ends of the foil. Areas of the foil adjacent the ends of the coil must be cleaned and then tinned. A soldered joint must then be made between the tinned areas and the lead-in wires. This procedure is expensive and time consuming because of the cleaning, tinning and soldering operations which are required. Furthermore the inherent physical weakness of a soldered joint between thin foil and Wire and the inevitable variations in quality of workmanship are not conductive to uniformly good wafer coil production. Finally, the technique is largely manual and most difi'icult to adapt to high speed automatic production.

I have now discovered that a terminal strip should be disposed at the ends of the roll in immediate contact with the. foil to eliminate these problems. Rows of tabs protrude outwardly from the strip; some of these can be forced through the foil to grasp the lead-in wires, and a distinct row of tabs can be forced through to attach the terminal strip to the roll. The tabs which grasp the lead-in wires are then butted down over these wires either before or after the wafer coils have been sliced. The tabs which attach the terminal strip to the winding roll are butted down against the foil before slicing.

From the foregoing it is apparent that many of the time consuming operations in fabricating wafer coils, particularly the individual soldering steps, can be eliminated. Greater automation can be introduced into the manufacture of these coils and substantial cost reduction can be realized.

The primary object, therefore, of the present invention 3,163,840 Patented Dec. 29, 1964 is to improve lead-in wire connections for wafer coils.

And yet another object of my invention is to reduce the cost of wafer coils by elimination of manual operations in their fabrication.

Another object of my invention is to eliminate soldered joints between lead-in wires and the ends of the wafer coils.

A feature of this invention is interposing a terminal strip within the convolutions of the rolled foil before the latter has been sliced into water coils.

And yet another feature of my invention is attaching the terminal strip to the foil by means of outwardly projecting tabs.

The many other objects, features and advantages of the instant invention will become manifest to those conversant with the art upon reading the following spe; cification when taken in conjunction with the accompanying drawings wherein preferred embodiments of my invention are shown and described by way of illustrative examples. Of these drawings:

FIGURE 1 is a perspective view of a terminal strip showing the disposition of tabs which can be used for making connections to lead-in wires and the convolutions of foil.

FIGURE 2 is a perspective, partially broken away, of a roll from which wafer coils can be sliced, the terminal strip of my invention being included therein.

FIGURE 3 is a perspective view of a wafer coil which has been sliced from the roll and has lead-in wires extending from the terminal connectors.

FIGURE 4 is a cross sectional view partially broken away, taken along the lines 44 of FIGURE 3.

Referring now to FIGURE hot the drawings, a terminal strip 12 of the type which I prefer to use at the originating and terminating ends of the roll from which the wafer coils are sliced is shown. The strip is preferably made of copper or other conducting metal, and it may be in the order of 0.015 inch thick. The material and thickness may, of course, be varied depending upon size and type of the connection which is to be made to the strip. Punctured or struck outwardly from the strip are two separate series of tabs. The first series of tabs, of which tabs 13 are typical, are designed to be punched through a superjacent convolution of the roll and butted down against the foil. The second series of tabs, of which tabs 14 are typical, are designed to puncture the same convolution of foil and accept lead-in wires. The tabs 14 are preferably arranged in parallel rows, spaced apart by a distance substantially equal to the diameter of the lead-in wire which is to be attached. Although the tabs are shown as being of a triangular shape, square, rounded or other shapes may be used also. Certain advantages are derived from the use of pointed tabs, however, since they are easily forced through the foil.

The incorporation of terminal strips such as the one which is illustrated in FIGURE 1 into a roll from which water coils are to be sliced may be understood further by reference to FIGURE 2. In FIGURE 2, a completed roll 15 from which the wafer coils can be sliced is shown. The roll 15 is formed by placing the terminal strip 16 over the originating end of the foil. The respective rows of tabs are then forced through the foil and the foilgraspingrow is butted back so that the terminal strip is secured. The series of tabs correspond made, the terminal strip of my invention is placed near the leading edge of the foil with the ends of the tabs pointing towards the core. The tabs are then forced through the foil and those which correspond to series 13 are bent back upon themselves to form a tight mechanical bond. The wrapping is then continued until the desired number of convolutions is made. An outer terminal strip, which can be identical to the inner terminal strip, is then placed beneath the terminating end of the foil. Again, the terminal strip is pressed upon the foil to cause all the tabs to puncture it. The foil tabs 13 are then bent over to fasten the strip securely to the foil. Although unnecessary in most instances, the tabs 13 or the terminal strips themselves may be welded or soldered to the foil to minimize contact resistance and to enhance the strength of the connection.

The entire roll is then wrapped with tape to hold the convolutions together. The sharp points of the wire tabs 14, which are left in an upright position, penetrate through the tape and are exposed in a position to accept the lead-in wire. Similarly, the tabs on the inner terminal strip corresponding to tabs 14 are in a position to accept the wires.

After the winding is completed in the manner described above, a Wafer coil as shown in FIGURE 3 is sliced from the roll. Portions of the two terminal strips are, of course, sliced from the roll also. The upstanding series of wire tabs 14 are, as noted above, suitably spaced to accept a lead-in wire 19 which is simply laid between the rows of tabs which are then bent over and swaged to provide solid electrical and mechanical contact. A lead-in wire 20 is attached to the inner terminal strip similarly.

In this manner, electrical connections to the ends of the wafer coils are available for utilization of the coil either by itself or as an element of a circuit.

In FIGURE 4, the ruggedness of the connections made to the foil and their disposition relative to the coilcomponents are shown. disposing the terminal connectors automatically rather than manually soldering wires to the foil is apparent. Positive contact between the foil and the terminal wires is assured and the cost of the terminal strips is insignificant when compared to that of the materials and labor which were used previously. Although it has been stated that the various tabs may be soldered or welded to the foil, this expedient is not necessary in most applications. Insertion of the strips at the beginning and end of the winding operation is relatively simple and fast and contributes greatly to reducing the cost of fabricatingthe coils. A wrapping of tape 31 holds the coil together and the turns 32 of the coil are insulated from each other by insulator 33.

It is apparent that modifications and changes may be made within the spirit and scope of the instant invention but it is my intention however only to be limited by the scope of the appended claims.

As my invention I claim:

1. An electromagnetic coil comprising: a convoluted spiral of thin metal foil; a thin layer of insulating material positioned between the convolutions of said foil; a terminal comprising an elongated metal strip interposed within the convolutions of said foil and extending along Furthermore, the adaptability to the length of said coil; means adapted to grasp lead-in wires positioned on said metal strip, said means comprising a laterally extending raised double row of spaced apart tabs passing through a superjacent winding of the foil of said coil; laterally extending means disposed substantially in parallel With said laterally extending rows of spaced apart tabs; said laterally extending means positioned on said elongated strip for attaching said metal strip to said foil.

2. An electromagnetio coil comprising: a convoluted spiral of thin metal foil; a thin layer of insulating material positioned between the convolutions of said foil; a terminal comprising an elongated metal strip interposed within the outer convolutions of said foil and extending along the length of said coil; means for grasping lead-in wires positioned upon said metal strip, said means comprising a laterally extending row of tabs passing through a superjacent convolution of the foil of said coil and adapted to overlap a lead-in wire disposed therein; laterally extending means disposed substantially parallel with said laterally extending roW of spaced apart tabs; said laterally extending means positioned on said elongated strip for attaching said metal strip to said foil.

3. A wafer coil comprising: a convoluted winding of foil; a lead-in wire and a metallic strip contacting an end of said foil, said metallic strip having a first and a second series of tabs, at least one tab of said first series passing through and overlapping said foil to form a firm mechanical connection thereto; said second series of tabs including at least two tabs spaced apart by substantially the width of said lead-in wire, said two tabs overlapping said lead-in wire to form a firm mechanical attachment thereto.

4. A wafer coil comprising: spirally wound sheets of foil and insulating material; a first conducting strip having a first and a second series of integral tabs, said first conducting strips being disposed adjacent one end and between said foil and insulating material, said second series of tabs passing through said foil adjacent one end and overlapping said foil to form a firm mechanical connection thereto; a first lead-in wire; said second series of tabs including two sets of tabs spaced from each other and passing through said foil and overlapping said first lead-in wire to form a firm mechanical connection there to; a second conducting strip similar to said first conducting strip attached adjacent the other end of said foil and disposed between said foil and said insulating material; a second lead-in wire attached to and disposed relative to said second conducting strip in the same manner as said first lead-in wire is attached to and disposed relative to said first conducting strip.

References Cited by the Examiner UNITED STATES PATENTS 2,072,635 3/37 Halgason et al. 339-278 2,091,920 8/37 Godsey 317-260 X 2,355,788. 8/44 Dunleaveyet a1. 317-260 X 2,451,393 10/48 Kershaw 339-276 X 2,779,928 1/57 Jeflfry 336-192 2,869,052 1/59 Ness 317-260 X JOHN F. BURNS, Primary Examiner, 

3. A WAFER COIL COMPRISING: A CONVOLUTED WINDING OF FOIL; A LEAD-IN WIRE AND A METALLIC STRIP CONTACTING AN END OF SAID FOIL, SAID METALLIC STRIP HAVING A FIRST AND A SECOND SERIES OF TABS, AT LEAST ONE TAB OF SAID FIRST SERIES PASSING THROUGH AND OVERLAPPING SAID FOIL TO FORM A FIRM MECHANICAL CONNECTION THERETO; SAID SECOND SERIES OF TABS INCLUDING AT LEAST TWO TABS SPACED APART BY SUBSTANTIALLY THE WIDTH OF SAID LEAD-IN WIRE, SID TWO TABS OVERLAPPING SAID LEAD-IN WIRE TO FORM A FIRM MECHANICAL ATTACHMENT THERETO. 